Technical Field
This invention relates to a drive system and an image forming apparatus, such as a copier, a printer, a facsimile machine, or a multifunctional machine having multiple functions of these devices, etc., including the drive system.
Related Art
In an image forming apparatus, many drive systems (i.e., drive sources) are generally employed to execute an image forming operation. For example, these drive systems are used to drive a photosensitive body, a transfer belt, or the like, for example. These drive systems usually generate a noise during an image forming process, thereby raising a problem. That is, since many components are mechanically connected to each other, noise may occur due to vibration of these components or the like when drive force is transmitted to these components from the drive system.
Many attempts have been made to eliminate or reduce such noise. For example, as shown in FIG. 4, a motor 200 acting as a drive system provided in an image reading unit is fixed to a supporting plate 201 with a pair of motor fixing screws 202 to suppress vibration of a drive unit employed in an image forming apparatus. The supporting plate 201 is fixed to a housing, not shown, at three places via multiple vibration absorbers 203 using multiple supporting plate fixing screws 204, respectively, for example.
On a rear side of the supporting plate 201, opposite a front side on which the motor 200 is held, a drive force output gear, not shown, and a driving pulley 206 are placed. Drive force from the motor 200 is accordingly transmitted via the drive force output gear from the motor 200 to the driving pulley 206. The driving pulley 206 then transmits the drive force to a belt 207 wound therearound. In the conventional image reading unit, a tilting angle adjusting screw 210 is also disposed on the supporting plate 201 as well to adjust an inclination of the supporting plate 201 by changing a fastening degree thereof not to excessively tilt toward the housing. With this arrangement, amplification of the vibration of the supporting plate 201, generally caused when the position of the driving pulley 206 deviates and meshing with the belt 207 deteriorates, is inhibited.
In another conventional attempt, various vibrations occurring in an image forming apparatus are separated into those that generate low-frequency noise and those that generate the high-frequency noise generally deemed unpleasant, respectively. Then, the high-frequency sound is rendered inaudible by enlarging the low-frequency sound at the same time as a countermeasure to reduce the sound, movement of a motor is smoothed by reducing a stepping angle of the motor or sound occurring inside walls is absorbed by placing sound absorbing material thereon, for example.
These countermeasures taken to either absorb the above-described vibrations and/or the sound or obscure the high-frequency sounds or the like have been successful to a certain extent in suppressing noise in the conventional image forming apparatus. However, since there exist various types of image forming apparatuses each having multiple drive systems for driving various mechanisms, respectively, installed therein, the above-described countermeasures are not always completely effective for it is generally preferable to prepare various countermeasures against noise employable in a greater number of types of image forming apparatuses.